Slicing the zebrafish eyes

Sometimes you volunteer to help a cause because it seems like the right thing to do, even if it is a little abstract. Sometimes you get to see firsthand exactly what your work and donations accomplish.

By CYNTHIA STEAD

capecodtimes.com

By CYNTHIA STEAD

Posted May. 22, 2014 at 2:00 AM

By CYNTHIA STEAD

Posted May. 22, 2014 at 2:00 AM

» Social News

Sometimes you volunteer to help a cause because it seems like the right thing to do, even if it is a little abstract. Sometimes you get to see firsthand exactly what your work and donations accomplish.

I went with a group of Lions from the Mid-Cape to see how our support of the Massachusetts Lions Eye Research funds are utilized. The Mass. Eye & Ear Infirmary (MEEI) is an international research center in Boston. It invited us to tour the research facilities to see how the proceeds from those "Pennies for Sight" jars on checkout counters are spent. To date, the Lions have collected and given about $5.5 million to support research on hereditary blindness and eye disease.

Dr. Qin Liu gave the Lions a brief overview of what their research was seeking to accomplish. Her research centers on Inherited Retinal Disease (IRD), which affects the retina, a film inside the eye which covers light receptors that allow sight. There are several types of blindness in this category — macular degeneration and retinitis pigmentosa are two common types. Other types are syndromic, with blindness occurring with other conditions. Usher's Syndrome is a conjunction of vision loss and deafness, for example.

Within the 3 billion base pairs in the human genome, about 99.9 percent are common to all humans; only 0.1 percent decide uniqueness. These genes, about 3 billion base matched pairs, are studied to find irregularities, which cause IRD. About 25,000 pairs in the genome are studied for "spelling errors." The paired sequences should go AA, BB, CC, ED, EE ... and the mismatch is a marker for hereditary disease.

By reverse engineering from the condition to the irregularity, researchers can find the mutations or deficiencies that are the root of the disease. Constant progress is made on identifying these various irregularities. Just last week, two new mutations were identified and have been submitted to medical journals.

The MEEI takes about 3,000 blood samples each year to sequence the genomes of people with IRDs to attempt to identify the flawed gene to develop individual genetic therapy. These sequencings are Genetic Eye Disease Panels or GEDi (pronounced like the Star Wars warriors) and the catalog of anomalies is the "ENCyclopedia Of DNA Elements," or ENCODE.

We walked through the laboratories to look at the equipment used to produce these data. A machine about the size of a photocopier can sequence 12 GEDi blood samples in two days, running day and night, for a cost of $500. A machine about the size of a dorm refrigerator can process 16 samples after running for two weeks. And a machine about the size of a minivan can do a whole genome sequence — all 3 billion parts, for about $5,000, and this is all while running at the fastest speeds computers can produce.

We also visited the tissue labs where fish are bred to replicate eye conditions seen in patients. Tiny zebrafish breed in a warm room and the yolks of their tiny eggs are injected with molecules blocking the genes of interest and luminescent dyes so the injection can be tracked when examined.

When I said that the tiny glass needles used to do this must be thinner than a human hair, the researcher enthusiastically yanked out one of her long curls so we could compare them under the microscope — and the needle was thicker by an infinitesimal amount.

When the zebrafish mature, their eyes are sliced at 1 micrometer thickness in a robotic mandolin slicer at the cellular level to create tissue samples, which then are used to study the structural compositions of the photoreceptor cells. By blocking the same genes in fish that are mutated in patients, the researchers can study the mutations and anomalies, which can be used to help understand the disease in humans, allowing development of gene therapies for hereditary blindness.

So if you see Lions with buckets collecting "Pennies for Sight" over this Memorial Day weekend, consider that it takes about a half-million pennies to process a single whole genome sequence, let alone the cost of a machine to do the processing. Mass. Eye & Ear thanks you for your support.

Cynthia E. Stead of Dennis is a member of the Dennis-Harwich Lions and executive director of Sight Loss Services in West Dennis. She can be reached at cestead@gmail.com.